They did not show a picture or how big is the server, but based on your
remarks it is small enough to fit in modest room.

I assume the Intra-links with the Blue Gene might be proprietary or
IB. What does clustering system Intra-links has do to
with the Ethernet network connection.

I assume still some of the users in TJW lab may want to connect with
higher speed Ethernet to this server, very likely you will need
links longer than 100 m. In addition higher speed Ethernet may be used
to cluster several Blue Gene system for fail over,
redundancy, disaster tolerance, or higher performance which will
require links longer than 100 m.

As you could see here the form factors which allow you to go >100 m
will be several time larger and not compatible
with the higher density solution based on nx10G. Linear nx10G as given
in http://www.ieee802.org/3/ba/public/jan08/ghiasi_02_0108.pdf
can extend the reach to 300 m on OM3 fiber and relax the transmitter
and jitter budget.

You have stated strongly you see no need for more than 100 m, but we
have also heard from other who stated
there is a need for MMF for more than 100 m especially if you have to
change the form factor for more than
100m! Like FC and SFP+ we can define limiting option for 100 m and
linear option for 300 m, and
let the market decide.

You are missing my point. Even the
best
case stat, no matter how you twist it in your favor, is based on
distances
from yesterday. New servers are much smaller, require shorter
interconnect
distances. I wish you could come to see the room where current #8 on
the top500 list of supercomputers is (Rpeak 114 GFlops), maybe you'll
understand
then.

Instead of trying to design
something
that uses more power and goes unnecessarilly longer distances, we
should
focus our effort towards designing energy efficient, small footprint,
cost
effective modules.

Petar; Depending on the sources of
link
statistics, 100m OM3 reach objective actually covers from 70% to 90% of
the links, so we are talking about that 100m isnot even close to 95%
coverage.RegardsFrankFrom: Petar Pepeljugoski
[mailto:petarp@US.IBM.COM]
Sent: Friday, March 14, 2008 5:09 PM
To:STDS-802-3-HSSG@listserv.ieee.org
Subject: Re: [802.3BA] Longer OM3 Reach Objective
Hello Jonathan,
While I am sympathetic with your view of the objectives, I disagree and
oppose changing the current reach objective of 100m over OM3 fiber.
From my previous standards experience, I believe that all the
difficulties
arise in the last 0.5 dB or 1dB of the power budget (as well as jitter
budget). It is worthwhile to ask module vendors how much would their
yield
improve if they are given 0.5 or 1 dB. It is responsible for most yield
hits, making products much more expensive.
I believe that selecting specifications that penalize 95% of the
customers
to benefit 5% is a wrong design point.
You make another point - that larger data centers have higher bandwidth
needs. While it is true that the bandwidth needs increase, you fail to
mention is that the distance needs today are less than on previous
server
generations, since the processing power today is much more densely
packed
than before.
I believe that 100m is more than sufficient to address our customers'
needs.
Sincerely.

I am a consultant with over 25 years experience in
data center
infrastructure design and data center relocations including in excess
of
50
data centers totaling 2 million+ sq ft. I am currently engaged in
data
center projects for one of the two top credit card processing firms and
one
of the two top computer manufacturers.

I'm concerned about the 100m OM3 reach objective, as it does not cover
an
adequate number (>95%) of backbone (access-to-distribution and
distribution-to-core switch) channels for most of my clients' data
centers.

Based on a review of my current and past projects, I expect that a 150m
or
larger reach objective would be more suitable. It appears that some
of the
data presented by others to the task force, such as Alan Flatman's Data
Centre Link Survey supports my impression.

There is a pretty strong correlation between the size of my clients'
data
centers and the early adoption of new technologies such as higher speed
LAN
connectivity. It also stands to reason that larger data centers
have
higher bandwidth needs, particularly at the network core.

I strongly encourage you to consider a longer OM3 reach objective than
100m.